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2.1 Introduction
This section describes supported Modbusr functions
and lists Modbusr registers and message codes.
WARNING
Unintended operation when applying the
communications protocol can cause
severe injury, death, or equipment
damage. Understand the following before
designing the system: (1) the system
application
requirements,
communications protocol, and
equipment manufacturers' specifications
and operating limits.
Ensure the accuracy of commands that
update controller settings or affect generator
management or transfer switch function.
Perform control system and software
qualification tests to ensure that the system
operates
controlled
reliably, and as intended.
2.2 Modbus Functions
The controller supports the Modbusr functions listed in
Figure 2-1.
2.3 Modbus Protocol Tables
The tables in Section 2.4 document the controller
information available using the Modbusr protocol.
Modbusr
Function Function Name
03
Read Holding Registers
06
Preset Single Register
16
Preset Multiple Registers Sets the value of a sequence of registers. Use this function to set all data occupying
Figure 2-1 Supported Modbusr Functions
Modbusr is a registered trademark of Schneider Electric.
TP-6208 4/03
(2) the
(3) the
equipment
safely,
Description
Reads a single register or a range of registers.
Sets the value of a single register. Use this function to set all data occupying a single
register.
multiple registers. The maximum number of registers is 16.
Section 2 Modbus Registers
In the following tables all word (16-bit) expressions are
integers unless otherwise noted and are shown in
decimal notation unless otherwise noted. Hexadecimal
expressions begin with 0x.
standard 8-bit ASCII character set. Unspecified bytes
are undefined, such as the high (most significant) byte of
holding registers that contain byte data in the low (least
significant) byte.
The tables include the following items.
Register. Modbusr registers are 16-bit registers and
are numbered consecutively.
Data Description. The Data Description column
describes the information located at the address.
Access. The Access column shows the type of access
allowed to the register. RO is read only, WO is write only,
and RW is read and write.
Data Type. If multiple registers are used, the Type/Size
column shows the number of WORDS used, and the
Range/Units column provides a breakdown of the
information available within the parameter.
Range/Units. This column lists additional information
about the register type when applicable. For example, if
multiple WORDs are used, this column describes the
information stored in each WORD. It also lists the units
for measurements which have them, the range for valid
input or output when applicable, and the the scale factor
for some parameters. Bit 0 is the least significant bit and
bit 15 is the most significant.
Characters are in the
Section 2 Modbus Registers
5
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